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Exposure to seasonal flu weakened armour against H1N1
Faulty antibodies from previous infections boosted severity of swine flu in the middle-aged.
Full text: http://www.nature.com/news/2010/1012....2010.649.html
Janelle Weaver
One of the puzzles of last year's H1N1 'swine flu' pandemic ? which caused thousands of deaths worldwide ? was that seemingly healthy middle-aged adults were hit hardest. A study has now shown that previous infection with other, seasonal, influenza strains primed patients' immune systems to harm their bodies rather than to mobilize against the new threat.
The study, published online today in Nature Medicine<sup>1</sup>, began with a hunch that antibodies from past encounters with pathogens might have determined the severity of H1N1 cases.
Exposure to viruses causes the body to produce antibodies that fight off infection. These proteins continue to circulate in the bloodstream and can recognize new invaders that resemble past pathogens. For example, the 2009 H1N1 episode spared many elderly people because they had already encountered a related H1N1 strain more than half a century ago, which had armed them with defensive antibodies. But curiously, young children infected with H1N1 who had little or no prior infection with influenza showed milder symptoms than did middle-aged adults.
After observing these phenomena, paediatrician Fernando Polack of Vanderbilt University in Nashville, Tennessee, and his team explored past exposure to pathogens. They found that pre-existing antibodies in infected middle-aged people recognized the 2009 H1N1 virus, but attacked organ tissue rather than defending against the invader.
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Faulty antibodies from previous infections boosted severity of swine flu in the middle-aged.
Full text: http://www.nature.com/news/2010/1012....2010.649.html
Janelle Weaver
One of the puzzles of last year's H1N1 'swine flu' pandemic ? which caused thousands of deaths worldwide ? was that seemingly healthy middle-aged adults were hit hardest. A study has now shown that previous infection with other, seasonal, influenza strains primed patients' immune systems to harm their bodies rather than to mobilize against the new threat.
The study, published online today in Nature Medicine<sup>1</sup>, began with a hunch that antibodies from past encounters with pathogens might have determined the severity of H1N1 cases.
Exposure to viruses causes the body to produce antibodies that fight off infection. These proteins continue to circulate in the bloodstream and can recognize new invaders that resemble past pathogens. For example, the 2009 H1N1 episode spared many elderly people because they had already encountered a related H1N1 strain more than half a century ago, which had armed them with defensive antibodies. But curiously, young children infected with H1N1 who had little or no prior infection with influenza showed milder symptoms than did middle-aged adults.
After observing these phenomena, paediatrician Fernando Polack of Vanderbilt University in Nashville, Tennessee, and his team explored past exposure to pathogens. They found that pre-existing antibodies in infected middle-aged people recognized the 2009 H1N1 virus, but attacked organ tissue rather than defending against the invader.
[...]